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Overpass team tackles street design

FOREST HILLS—The design team for the Casey Overpass replacement project started evaluating alternatives for at-grade traffic patterns, the first of many options to be explored in the redesign of the area.

At-grade, or street-level, traffic patterns will dictate what the new overpass will look like or even if one will be included in the final design.

“Reconciling that street network is crucial” to shaping the final design, Andrea D’Amato, part of the design team, said at the June 2 meeting at English High.

The Monsignor William J. Casey Overpass is the elevated section of Route 203 over Washington and South streets, next to the Forest Hills MBTA Station. Built in the 1950s, it has become too expensive to maintain and is now due for replacement. The Massachusetts Department of Transportation (MassDOT) says the overpass is still safe to use.

After the current overpass comes down, a new overpass could be built, or a street-level parkway could be paved, a decision the design team has not made yet. Each option presents benefits and challenges to users: a new overpass would more likely be more efficient for regional traffic, while an at-grade parkway likely would be more accessible to pedestrian and bicycle traffic.

The design team presented three basic options for at-grade traffic: traditional crossings with traffic signals and no left-hand turns at either South or Washington streets; a “bow-tie” design that would shift left-turn lanes away from the traffic signals; and an innovative “continuous flow” alternative that would involve crisscrossing traffic in order to make a left-hand turn.

The clear favorite, the bow-tie model would have two turn signals at South and Washington streets, with no left-turn lanes. After the lights, U-turn lanes would be cut into a wide median, allowing for a change in traffic direction and permitting easy right-hand turns onto Washington and South streets.

The bow-tie name comes from the shape of the proposed median—narrow at the intersections, then wider on either side to allow for the U-turn lane.

The second option would include traffic lights at South Street and Washington Street, neither of which would allow left-hand turns onto either of those streets. No median was specified in the idea.

The continuous flow option would involve crossing several lanes of oncoming traffic to make a small left-hand turn.

“It’s new and exciting, but it could be confusing,” WAG member David Hannon said of the continuous flow model.

Options for Shea Circle, the rotary at the western end of the Casey Overpass, were also presented. Some involved a complete razing of the existing circle, including the removal of old and well-established trees, while others tried to streamline the approaches to the rotary to improve traffic flow.

A member of the design team stated that Shea Circle fits into the area “like a puzzle piece,” meaning that any option chosen for the rotary could be accommodated in any final design the WAG chooses.

The design team also presented other traffic pattern options that have already been discarded, to show the WAG members what ideas have already been considered and discarded.

Several potentially problematic MBTA structures at the Forest Hills T Station—air vents, stairwells and a booth—could be moved to accommodate the final design, the design team said. Those moves would be limited due to MBTA restrictions, but the fact that they are even possible was welcomed by the WAG.

One of the possibilities under consideration includes an expansion of the western bus bay at Forest Hills Station, which would free up traffic flow on Washington Street and allow for the construction of a multi-use pedestrian and bike path between the Southwest Corridor Park and the Arnold Arboretum.

The current project schedule includes: coming up with a replacement concept by October; designing the plan from then into 2013; then demolishing the overpass and building the replacement by June 2016.

The WAG consists of residents and elected officials and has members representing about 25 area organizations. A complete list of WAG members is available at the project website, www.massdot.state.ma.us/caseyoverpass.